Brazilian soils destined for fodder production are infertile and acidic and contain toxic levels of aluminum (Al), which cause a reduction in growth of the root system and aerial plant parts. The main aim of the present pot trial was to determine ultrastructural and developmental changes in root and leaf tissues of Urochloa brizantha, when grown in an acid Oxisol containing varying levels of Al. The experimental design was a 3 × 5 factorial arrangement, involving 3 cultivars of U. brizantha (Marandu, Paiaguás and Piatã) and 5 concentrations of Al in the soil (0.2, 0.4, 0.8, 1.6 and 3.2 cmol/dm3), with 4 replications; a total of 60 pots. All cultivars responded negatively to increasing Al concentration in the soil, even in small amounts. Root ultrastructures were damaged even at concentrations of 0.4 cmol Al/dm3, primarily in the conducting tissues (xylem and phloem) and epidermal cells. Shoot development and leaf tissues were also negatively affected. In general, plant development and ultrastructure of root and leaf tissues in all 3 cultivars of U. brizantha were impaired when grown in the presence of Al at doses >0.2 cmol/dm3 in the soil.

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Introduction:In order to characterize Eucalyptus species for diverse purposes, it is necessary to analyze it in an ultrastructural and physiological way, aiming a faster and more precise selection of the possible properties and utilities of the species. Objective: The objective was to observe the physiological and ultrastructural characteristics of leaves of eucalyptus clones destined for matrix selection.

One of the main responsible attributes for the good quality of seedlings is its cultivation in substrates with a good drainage and nutrients availability. This work aimed to study the production of pepper seedlings with different doses of organic compounds in substrate. The experiment was carried out in August, 2018, at Educational Foundation of Andradina, in Andradina, São Paulo State, Brazil. The experimental design was completely randomized, in a 2x5 factorial scheme, with two organic substrates: peaty exhausted compound (EC) and coconut fiber compound (CC), in five different concentrations: null %; 25%; 50%; 75% and 100%, with five repetitions, in total of fifty plots. The increase in the concentration of organic compounds in production of pepper seedlings promoted a greater development. It is recommended using 70% of peaty exhausted in the composition of substrate to the production of pepper seedlings and using 100% of coconut fiber in the composition of the substrate to the production of pepper seedlings.

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Brazilian soil presents serious problems with plant production, due to its low fertility and high acidity content, besides that the toxicity caused by the chemical element aluminum. To overcome these problems, agricultural gypsum is used to neutralize the action of aluminum and, together with the assistance of nitrogen sources, ensures greater forage productivity. The objective of this work was to recover a pasture area with the application of agricultural gypsum associated with nitrogen fertilization. The experimental design was in randomized blocks with four replications, in a 2x4 factorial scheme with 50 kg ha-1 of N in the form of ammonium nitrate and 50 kg ha-1 of N in the form of urea, plus four doses of agricultural plaster, of which: 0; 750; 1500 and 3000 kg ha-1 in pasture installed in Urochloa humidicola. The dose of 1884 kg ha-1 of gypsum provided the highest concentration of calcium when applied in conjunction with ammonium nitrate. For sulfur, a linear response was observed, regardless of the nitrogen source used. The use of urea significantly increased the nitrogen levels in the leaves. The application of gypsum, regardless of the nitrogen source, provided a linear response in the calcium and sulfur levels in the leaves.